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Age related change of optokinetic nystagmus in healthy subjects: a study from infancy to senescence

C Valmaggia¹, A Rütsche¹, A Baumann¹, C Pieh¹, Y Bellaiche Shavit¹, F Proudlock² and I Gottlob²

¹ Department of Ophthalmology, Kantonsspital, St Gallen, Switzerland
² Department of Ophthalmology, University of Leicester, Leicester, UK

Correspondence to:
Correspondence to:
Christophe Valmaggia MD
Department of Ophthalmology, Kantonsspital, CH-9007 St Gallen, Switzerland; christophe.valmaggia{at}kssg.ch

Background: Optokinetic nystagmus (OKN) gain is asymmetrical between temporal to nasal (TN) and nasal to temporal (NT) stimulation in infancy and decreases at older ages. The age at which OKN gain becomes symmetrical and decreases is debated. The aim was to investigate OKN over the whole lifespan in a large sample of healthy subjects.

Methods: In a prospective, cross sectional study OKN was tested monocularly using TN and NT small field stimulation. Stimulation velocity was 15°/s and 30°/s for children aged under 1 year (n = 97), and 15°/s, 30°/s, 45°/s, and 60°/s for older subjects (1–9 years, n = 66; 10–89 years, n = 86). Gain was measured using infrared oculography.

Results: Significant OKN gain asymmetry in favour of TN versus NT stimulation was found during the first 5 months of life (p<0.05). Only at 11 months of age was OKN symmetrical in 100% of the subjects. The percentage of children with symmetrical OKN decreased with increasing stimulus velocity. OKN gain increased in the second and third years (p<0.05 for 15°/s), remained stable until 50 years of age, and showed a small but significant decrease afterwards for the tested velocities (between 6% and 18%, p<0.05).

Conclusions: Infrared oculography is an accurate method to assess OKN, especially in children. Knowledge about change of OKN in healthy subjects could be helpful to interpret OKN in patients with abnormal binocular vision or lesions of the central nervous system.

Abbreviations: DTN, dorsal terminal nucleus; NOT, nucleus of the optic tract; NT, nasal to temporal; OKAN, optokinetic after nystagmus; OKN, optokinetic nystagmus; TN, temporal to nasal

Keywords: optokinetic nystagmus; age; asymmetry

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